The optimism of Venus Williams before she began the defence of her WTA Championships title today was swiftly punctured by a 3-6, 7-6, 6-2 defeat to Elena Dementieva. "Obviously Serena and I are playing at a level that would keep us here for quite a few years longer," she had said before facing the Russian.

She continued: "At the end of the year, I'm feeling like I'm ending on a high note. That's definitely high energy. Good acapella." That might apply for her sister Serena, but for Venus, it was singing in the dark, more like.

Not only did this setback create a strong possibility that she will lose this title when she plays Serena on Wednesday it gave credence to those who suggest that major titles are getting beyond the 29-year-old. It is eight months since she captured any title at all. Since the Wimbledon final in July, she has reached one semi-final in seven tournaments, and today after leading the Olympic champion by a set and 3-1 her standard fell away so suddenly that the match was soon beyond her reach. "I just didn't put enough balls in court," she kept repeating. "There were lots of reasons for that," she added, though she would not elaborate.

Certainly her movement became more sluggish and her stroke preparation more pressured. Williams did break serve for 6-5 but could not close out the match, and after leading 2-0 in the tie-break she lost five points in a row, flapping her hands in a gesture of fatalism.

It did, indeed, signal the increasingly inevitable. Dementieva, who had been tense for an hour or so, relaxed and bestrode the court in the final set, launching muscular drives and moving with increasing zest. "I felt very emotional at the end," she said. "It's a long time since I have beaten her." Williams too was emotional, but differently. "I have to put it right tomorrow," she said. But will her sister let her, having beaten Svetlana Kuznetsova, the French Open champion, 7-6, 7-5?